Aircraft avionics rack with interconnection platform

ABSTRACT

An aircraft avionics bay provided with at least one shelf (4) that includes: a support platform (5); retention seats (12) for a rack-mountable electrical module (6) each including a module connector (14); an external connection interface (7); an interconnection platform (9) extending substantially parallel to the support platform (5), on the side opposite the retention seats (12), the interconnection platform (9) supporting conductive connection tracks (28); a plurality of rear printed circuits (15), each rear printed circuit (15) extending opposite a module connector (14); the conductive connection tracks (28) of the interconnection platform (9) extending into each rear printed circuit (15) and to the external connection interface (7) via flexible conductors (18, 19).

CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage entry of PCT/EP2020/025268 filedJun. 9, 2020, under the International Convention and claiming priorityover French Patent Application No. FR1906195 filed Jun. 11, 2019.

TECHNICAL FIELD

The invention concerns the field of aeronautics and relates to avionicsbays of aircraft.

Avionics bays are electrical cabinets carried in an aircraft which makeit possible to house electrical or electronic equipment items, such ascomputers or other instruments, and also the electrical cablingconnecting these equipment items. These avionics bays are generally of aconsiderable size and contain numerous electronic or electricalequipment items close to one another, and also a large quantity ofcables. An avionics bay generally comprises a multirack device allowingthe equipment items to be inserted and removed while ensuring theirmechanical support and their electrical connection. These multirackdevices ensure a high level of safety in the management of theelectrical equipment items, both during normal operation and duringmaintenance phases.

PRIOR ART

Aircraft avionics bays generally comprise shelves for supportingelectrical or electronic equipment items.

Document U.S. Pat. No. 4,458,296 describes a shelf structure for anavionics bay. The shelf described comprises a support platform on whichthere are mounted retaining seats for a rackable electrical module, eachretaining seat comprising a connector. The connectors of all theretaining seats are connected to an external connection interfaceintended to be connected to the electrical circuit of the aircraft. Theconnection between the connectors of the retaining seats and theexternal connection interface is achieved by electrical cabling arrangedin various bundles held by ramps or by trunking.

Given the complexity of the electrical modules to be connected, thiscabling constitutes a considerable mass, bulk and cost which would beappropriate to reduce. Moreover, during the manufacture of the avionicsbays, this type of cabling demands numerous manual operations to beperformed by qualified personnel.

Documents FR2977447 and FR2927222 describe avionics bays partiallyaddressing the disadvantages described above.

SUMMARY OF THE INVENTION

The object of the invention is to improve the avionics bays of the priorart.

To this end, the invention is aimed at an aircraft avionics baycomprising an arrangement of racks intended for the integration ofelectrical equipment items and connections, this avionics bay beingprovided with at least one shelf which comprises:

a support platform;

retaining seats for a rackable electrical module, these retaining seatsbeing mounted on the support platform, each retaining seat comprising anend wall substantially perpendicular to the support platform, and amodule connector mounted on this end wall;

an external connection interface intended to be connected to theelectrical circuit of the aircraft and mounted on the support platformand connected to the module connectors.

Said shelf comprises:

an interconnection plate extending substantially parallel to the supportplatform, on the side opposite to the retaining seats, thisinterconnection plate bearing conductive connection tracks;

a plurality of rear printed circuits, each rear printed circuitextending opposite a module connector;

the conductive connection tracks of the interconnection plate extendinginto each rear printed circuit and into the external connectioninterface via flexible conductors.

In such an avionics bay, a considerable volume, accessibility and costgain is achieved by means of the arrangement of the interconnectionplate and of the rear printed circuits. No cable is necessary forconnecting the module connectors to the external connection interface.

The movable parts of the interconnection are reduced to a minimum, andthe interconnection function as a whole requires little or nomaintenance.

The manufacture of such an avionics bay is greatly simplified by doingaway with all the manual cabling operations involving the passage ofcables and the fixing thereof to ramps or trunking.

The invention thus allows rapid and reduced-cost manufacturing of anavionics bay for an aircraft that proves to be more reliable and requireless maintenance than the avionics bays carrying traditional cabling.

Moreover, aeronautical regulations currently tend to require, for safetyreasons, the multiplication of the cable paths in the interconnection ofthe avionics bays. This multiplication of the cable paths is easilyachieved within the avionics bay according to the invention, since theinterconnection plate offers a surface suitable for the multiplicationof the paths of conductive connection tracks without increasing the bulkor the mass of the avionics bay.

The invention thus allows the implementation of the new regulations foraircraft carrying more and more electronic and electrical hardware, thecomplexity of which hardware is increasing.

The avionics bay according to the invention can comprise the followingadditional features, alone or in combination:

each rear printed circuit is fixed to the module connector oppositewhich kit extends;

each rear printed circuit and its corresponding module connector arefixed on either side of a spacer;

the spacer comprises a flange wall extending perpendicularly to the rearprinted circuit and arranged on the periphery of the rear printedcircuit;

each module connector comprises pins connected to the rear printedcircuit to which it is fixed;

the pins of each module connector are connected to the correspondingrear printed circuit by rigid conductive rods;

the rigid conductive rods are crimped or welded in the correspondingrear printed circuit;

each retaining seat comprises a connection window made in its end wall,each module connector comprising a connection wall which is fixed to theend wall of the corresponding retaining seat by fixings screwed into thespacer, with the result that the module connector projects from theconnection window;

each rear printed circuit is connected to the conductive connectiontracks of the interconnection plate by a flexible printed circuit;

the external connection interface comprises an external connectionprinted circuit to which the interface connectors are connected, theexternal connection printed circuit being connected to the conductiveconnection tracks of the interconnection plate by a flexible printedcircuit;

the external connection interface comprises an external connection wallfixed substantially perpendicularly to the support platform, theinterface connectors and also the external connection printed circuitbeing fixed to this connection wall;

each interface connector comprises pins connected to the externalconnection printed circuit;

the pins of the interface connectors are connected to the externalconnection printed circuit by rigid conductive rods;

said rigid conductive rods are crimped or welded in the externalconnection printed circuit;

the flexible printed circuits connected to the rear printed circuits areconnected to the conductive connection tracks of the interconnectionplate via a detachable connector;

the flexible printed circuit connected to the external connectionprinted circuit is connected to the conductive connection tracks of theinterconnection plate via a detachable connector;

the interconnection plate, the rear printed circuits, the externalconnection printed circuit, and the flexible printed circuits are formedby a single printed circuit comprising rigid portions and flexibleportions;

the support platform is made up of two parallel planar crossmembersformed by two lateral profiles of the shelf;

the interconnection plate is fixed to the shelf by a flexible referencepotential setting fastener;

the interconnection plate comprises a protective cover fixed to theshelf and extending substantially over the whole surface of theinterconnection plate;

the interconnection plate is made up of a rigid printed circuit in whichthe conductive connection tracks are etched;

the avionics bay comprises a device for cooling by circulation of a gaspassing through the rackable electrical modules, and said shelfcomprises a ventilation wall which extends parallel to the supportplatform, the shelf forming a ventilation casing of the cooling device,between the support platform and the ventilation wall, theinterconnection plate being arranged opposite the ventilation wall;

the ventilation wall and the interconnection plate each compriseventilation through-orifices;

the interconnection plate comprises as many ventilation orifices as theventilation wall, each ventilation orifice of the interconnection platebeing opposite a ventilation orifice of the ventilation wall;

the interconnection plate comprises a protective cover fixed to theshelf and extending substantially over the whole surface of theinterconnection plate, this protective cover comprising ventilationthrough-orifices;

the ventilation wall comprises a ventilation window, the interconnectionplate closing off this ventilation window, the interconnection platecomprising ventilation through-orifices;

a tightness seal is clamped between the interconnection plate and theventilation wall, on the periphery of the ventilation window;

the interconnection plate comprises a protective cover fixed to theshelf and extending substantially over the whole surface of theinterconnection plate, this protective cover comprising ventilationthrough-orifices;

the protective cover comprises as many ventilation orifices as theinterconnection plate, each ventilation orifice of the protective coverbeing arranged opposite a ventilation orifice of the interconnectionplate;

the avionics bay comprises a device for cooling by circulation of a gaspassing through the rackable electrical modules, and the shelf warms aventilation casing of the cooling device, this casing being delimited bythe interconnection plate and the support platform, the interconnectionplate comprising ventilation through-orifices;

the interconnection plate comprises a protective cover fixed to theshelf and extending substantially over the whole surface of theinterconnection plate, this protective cover comprising ventilationthrough-orifices;

the protective cover comprises as many ventilation orifices as theinterconnection plate, each ventilation orifice of the protective coverbeing arranged opposite a ventilation orifice of the interconnectionplate;

the avionics bay comprises a protective shell for each rear printedcircuit, this protective shell comprising tabs for retaining theinterconnection plate;

the avionics bay comprises an equipment item in the facade of a shelf,this equipment item being connected by an additional flexible printedcircuit to the interconnection plate.

PRESENTATION OF THE FIGURES

Other features and advantages of the invention will become apparent fromthe following nonlimiting description with reference to the appendeddrawings, in which:

FIG. 1 illustrates an avionics bay according to the invention;

FIG. 2 shows a shelf of the avionics bay of FIG. 1;

FIG. 3 shows the shelf of FIG. 2, the module connectors and the externalconnection interface being demounted;

FIG. 4 shows the interconnection assembly of the shelf of FIG. 2;

FIG. 5 shows the shelf of FIG. 3 viewed from below;

FIG. 6 shows the shelf of FIG. 2 viewed in section;

FIG. 7 shows a reference potential setting fastener of the shelf of FIG.2;

FIG. 8 shows a tongue of the shelf of FIG. 2;

FIG. 9 shows the fastener of FIG. 7 viewed in section;

FIG. 10 illustrates a variant of the fastener of FIG. 7;

FIG. 11 shows the fastener of FIG. 10 mounted on a shelf;

FIG. 12 is a view similar to FIG. 6 for a second embodiment of theinvention;

FIG. 13 is a view similar to FIG. 6 for a third embodiment of theinvention;

FIG. 14 is an enlarged view of the box XIV of FIG. 6.

DETAILED DESCRIPTION

FIG. 1 is a schematic representation of an avionics bay 1 according tothe invention.

This avionics bay 1 comprises two lateral uprights 2, 3 between whichshelves 4 extend. Each of the shelves 4 is formed by a casing whosehollow part extends between a ventilation wall 10 and a support platform5 for rackable electrical modules 6 mounted on the shelf 4.

The electrical modules 6 are, for example, electrical or powerelectronics devices for calculation relating to the navigation, safety,air-conditioning functions, etc. These modules 6 are referred to asrackable, since they are mounted on the shelves 4 in a removable mannerby virtue of retaining seats (not shown in this schematic view ofFIG. 1) to facilitate the maintenance and the replacement of thesemodules. These rackable electrical modules 6 are also termedline-replaceable units (LRUs). They are, for example, modules inaccordance with aeronautical standard ARINC.

Each shelf 4 comprises, in addition to modules 6, an external connectioninterface 7 provided with interface connectors 8. The electrical circuitof the aircraft is connected to the avionics bay 1 via these interfaceconnectors 8.

The external connection interface 7 of each shelf 4 is connected to eachof the modules 6 mounted on this shelf 4 via an interconnection plate 9extending parallel to the support platform 5, on the side opposite tothe modules 6. In other words, the support platform 5 is situatedbetween the modules 6 and the interconnection plate 9, for each shelf 4.

In the present example, the avionics bay 1 also comprises a device forcooling by circulation of air. This cooling device makes it possible tomaintain the electrical and electronic equipment items of the modules 6at an acceptable temperature given their large number, their density andthe heat that they give off.

This cooling device organizes an air circulation shown schematically inFIG. 1 by means of arrows. In the present example, fresh air is injectedinto the avionics bay 1 via one of its uprights 2 and then isdistributed into the shelves 4 forming casings channeling this fresh airto pass through the modules 6. Various portions of each shelf 4 arepierced with ventilation through-orifices (not shown in this schematicview of FIG. 1) allowing the cooling air to pass through the module 6 inorder to cool it.

The heated air passing through the modules 6 is then recovered in theshelves 4, which discharge the hot air toward the other upright 3 of theavionics bay 1 in order then to be discharged from the avionics bay 1.

Flow separation walls 11 within the casings formed by the shelves 4 makeit possible to separate the fresh air and hot air flows in each shelf 4if necessary.

FIG. 2 shows one of the shelves 4 of the avionics bay 1. In this FIG. 2,the module 6 have not been shown. Only the retaining seats 12 intendedto receive these modules 6 have been shown in FIG. 2. In the presentexample, the retaining seats 12 are in accordance with standard ARINCand allow the mechanical fixing and the electrical connection ofcompatible modules 6. The mechanical locking is provided in particularby thumbwheels 13, while the electrical connection of the modules 6 isprovided by module connectors 14.

In the example illustrated in FIG. 2, five retaining seats 12 aremounted on the support platform 5 of the shelf 4, thus making itpossible to receive five rackable electrical modules, to fix them bymeans of the thumbwheels 13 and to electrically connect them to theelectrical circuit of the aircraft by virtue of the module connectors14. The thumbwheels 13 are arranged on the front part of the retainingseats 12, that is to say the part which is accessible to the user whenthe latter is facing the avionics bay.

As described above, the shelf 4 also comprises an external connectioninterface 7 provided with interface connectors 8 making it possible toconnect all the modules of the shelf 4 to the electrical circuit of theaircraft, in order to electrically supply, and communicate with, all themodules 6 which are intended to be mounted in the retaining seats 12.The external connection interface 7 is also fixed to the supportplatform 5.

The shelf 4 comprises, furthermore, a plurality of rigid rear printedcircuits 15. A rear printed circuit 15 is provided for each moduleconnector 14. Each of the rear printed circuits 15 is thus arrangedopposite the module connector 14 of a retaining seat 12. Each rearprinted circuit 15 and its corresponding module connector 14 are rigidlyfixed to one another.

The rear printed circuits 15 are each protected by a protective shell16. In FIG. 2, three of the rear printed circuits 15 have been shownwith their protective shell 16, while two of the rear printed circuits15 are shown without their protective shell 16 in order to reveal therear printed circuits 15.

The retaining seats 12 are each pierced with ventilationthrough-orifices 17 allowing the fresh air flow emanating from the shelf4 to pass through the module 6 which will be mounted on this retainingseat 12.

Each of the rear printed circuits 15, on the one hand, and the externalconnection interface 7, on the other hand, are connected to theinterconnection plate 9 (not visible in FIG. 2) by a flexible printedcircuit 18, 19.

Each protective shell 16 advantageously protects a rear printed circuit15 and also its flexible printed circuit 18.

The protective shells 16 are, furthermore, provided at their bottom withprotruding retaining tabs 61 or lugs in order to retain theinterconnection plate 9 once they have been installed at the rear oneach rear printed circuit 15. The protective shells 16 thus provide anadditional function of retaining the interconnection plate 9.

FIG. 3 shows the shelf of FIG. 2 with its module connectors 14 demountedand with its external connection interface 7 open.

Each of the retaining seats 12 comprises an end wall 22 extendingperpendicularly to the support platform 5, and in which a connectionwindow 20 is made. Each module connector 14 is mounted on a connectionwall 21 which is fixed (when the shelf is in its mounted position ofFIG. 1) to the edges of the connection window 20 such that the moduleconnector 14 projects from the connection window 20 in order to be ableto connect the module received in the retaining seat 12. The connectionwalls 21 and the module connectors 14 thus each extend perpendicularlyto the support platform 5.

The module connectors 14 can be of any suitable type for providing theconnection of a module 6 when this is inserted into the correspondingretaining seat 12 until butting against its end wall 22. The moduleconnector 14 can be in one piece or, by contrast, made up of a pluralityof subconnectors. These module connectors 14 are provided with pinsextending parallel to the support platform 5, in the direction of themodule installed on the retaining seat 12. These pins areinterconnection pins which are advantageously demounted and replaceable.These pins 60 are shown in more detail in FIG. 14.

For each retaining seat 12, the connection wall 21 is secured to therear printed circuit 15 by virtue of a spacer 23. The spacer 23 is heremade up of a flange wall extending perpendicularly to the rear printedcircuit and arranged on the periphery of the rear printed circuit. Theconnection wall 21 is fixed on one side of the spacer 23, and the rearprinted circuit 15 is fixed on the other side of the spacer 23, theprinted circuit thus being parallel to the connection wall 21. Theconnection wall 21 can advantageously be fixed to the end wall 22 byfixings screwed into the spacer 23.

The pins of the module connector 14 are connected to the correspondingrear printed circuit 15 by any cabling means such as by connection ofwelded conductors, or more advantageously by force-fitting technologiesof the press-fit type. The pins of each module connector 14 are thusdemountable and extended by rigid conductive rods which are crimped inthe corresponding rear printed circuit 15. These rigid conductive rodsare commonly termed “tulips”. The module connectors 14 are thus mountedand connected in a quick and reliable manner. The conductive rods 56 areshown in FIGS. 6, 12 and 13, and also in FIG. 14, which is an enlargedview of the box XIV of FIG. 6. The pins 60 of the connector 14 and theconductive rods 56 are connected by force-fitting.

The rigid fixing provided by the spacer 23 here allows the use of rigidconnections between the module connector 14 and the rear printed circuit15 and ensures the durability of these connections over time by virtueof a mounting in which the relative movements of the module connector 14and of the corresponding rear printed circuit 15 are not allowed.

FIG. 3 reveals the possibility of movement of the module connectors 14when they have been demounted from their connection window 20. Thismovement is allowed by the flexibility of the flexible printed circuits18. The fixing, for each module, of the connection wall 21 to theconnection window 20 preferably occurs by way of screws accessible fromthe inside of the retaining seat 12, that is to say from the front face(on the thumbwheels 13 type) of the shelf. An operator can thus easilygain access to a module connector 14 by extracting the module from aretaining seat 12, by unscrewing these screws, and by positioning theconnector 14 in its position of FIG. 3 by virtue of the flexibility ofthe flexible printed circuit 18.

As far as the external connection interface is concerned, the latter ismade up of a connection housing 24 comprising an external connectionwall 25 (which is shown demounted in FIG. 3). An external connectionprinted circuit 26 is fixed parallel to the external connection wall 25by virtue of spacers 27 and is connected to the flexible printed circuit19.

The interface connectors 8 (visible in FIG. 2) are connected to theexternal connection printed circuit 26 in a similar manner to the moduleconnector 14. The interface connectors 8 thus comprise pins (not shownin order to simplify the figures) connected by any suitable technique tothe tracks of the external connection printed circuit 26, and inparticular by force-fitting technology permitted by the externalconnection printed circuit 26 being rigidly retained with respect to theexternal connection wall 25. The pins of each interface connector 8 arethus extended by rigid conductive rods which are crimped in the externalconnection printed circuit 26. The pins of the interface connectors 8and these rigid conductive rods can be mounted in the same way as thepins 60 and the rods 56 of the module connectors 14 (that is to say inthe way illustrated in FIG. 14).

The external connection interface 7 thus provides, at the interfaceconnectors 8, the connection technology allowing all the pins of themodule connectors 14 to be connected to the electrical circuit of theaircraft. The connection housing 24 makes it possible, moreover, tohouse additional equipment items such as fuses, connectors or displaysintended for maintenance, these additional equipment items being able tobe directly mounted on the external connection printed circuit 26.

FIG. 4 illustrates the production of the electrical connection betweenthe module connectors 14 and the interface connectors 8. This FIG. 4shows an interconnection assembly, the flexible printed circuits 18, 19and rigid printed circuits 15, 26 of which have been shown, in a flatposition illustrating a preferred position for the manufacture of thisinterconnection assembly.

The rear printed circuits 15 and the external connection printed circuit26 are each connected to the interconnection plate 9 by virtue of theirrespective flexible printed circuit 18, 19. In the present example, theinterconnection plate 9 is a printed circuit bearing conductiveconnection tracks 28 connecting the flexible printed circuits 18 to theflexible printed circuits 19 and possibly certain flexible printedcircuits 18 to one another. The conductive connection tracks 28 extend,continuously or with possible interconnections, from the rear printedcircuits 15 to the external connection printed circuit 26.

In FIG. 4, only some conductive connection tracks 28 have beenschematically shown, it being understood that a large number of modules6 can be mounted on a shelf 4, this generating a large quantity ofelectrical connections of weak and high power to be provided between themodule connectors 14 and the interface connectors 8 or between twoconnectors 14. Since the area of the interconnection plate 9 is limitedonly by the area of the shelf 4 itself, this area of the interconnectionplate 9 can be adapted to these numerous conductive tracks 28 to besupported. The interconnection plate 9 can, moreover, be formed by aprinted circuit with a plurality of layers if the number of conductivetracks 28 so requires.

Each pin of a module connector 14 can thus be connected to a pin of aninterface connector 8 by a circuit passing through the rear printedcircuit 15, the flexible printed circuit 18, the interconnection plate9, to the flexible printed circuit 19, and to the external connectionprinted circuit 26.

The interconnection plate 9 comprises, moreover, a plurality ofventilation through-orifices 29 intended to participate in the functionof cooling the avionics bay.

The interconnection plate 9 comprises, furthermore, reference potentialsetting fasteners 30 making it possible both to mechanically retain theinterconnection plate 9 with respect to the corresponding shelf 4 and toelectrically ground the interconnection plate 9 with the metallicstructure of the shelf 4. The modules 6 and the external connectioninterface 7 can thus be grounded to the avionics bay 1 in a reliablemanner by conductive tracks of the interconnection plate 9.

According to a preferred feature, the interconnection plate 9, the rearprinted circuits 15, the external connection printed circuit 26 and alsothe flexible printed circuits 18, 19 are made in one piece. Theinterconnection assembly shown in FIG. 4 (with the exception of thefasteners 30) is thus formed by a single printed circuit which comprisesrigid portions 15, 9, 26 and flexible portions 18, 19. However, theinterconnection plate 9 can also be formed by a flexible printedcircuit.

An extremely rapid and reliable manufacture is thus permitted for thecomplete interconnection system of FIG. 4.

In a variant, if modularity properties are preferred for theinterconnection assembly, the flexible printed circuits 18 connected tothe rear printed circuits 15 can be connected to the interconnectionplate 9 via detachable connectors, thereby making it possible to removeor add rear printed circuits 15, and therefore module connectors 14,from or to the same interconnection plate 9.

Likewise, the flexible printed circuit 19 of the external connectionprinted circuit 26 can be either produced in one piece with theinterconnection plate 9 or, in a variant, connected by detachableconnectors making it possible to change the external connection printedcircuit 26 in order to replace it if it is defective, or to have thechoice of connecting various external connection interfaces 7 to thesame interconnection plate 9.

The flexible printed circuits 18, 19 here make it possible to connectelements perpendicular to one another. A weak bending stress is thusimposed on these flexible printed circuits 18, 19 which is a gauge ofreliability.

FIG. 5 shows the shelf 4 of FIG. 3, viewed from below. FIG. 5illustrates a first embodiment of the assembly of the interconnectionplate 9 with the shelf 4.

In this example, the shelf 4 forms a casing inside of which therecirculates the cooling air which enters and leaves the casing viaaeration openings 31. The support platform 5 delimits the upper part ofthis casing, whereas the ventilation wall 10 delimits the lower part ofthis casing, lateral profiles 32 moreover delimiting the lateral edgesof the casing.

The interconnection plate 9 is fixed opposite the ventilation wall 10 byvirtue of the reference potential setting fastenings 30 which are fixedto one of the lateral profiles 32 and also by additional fasteners 33whose function is only to clamp the interconnection plate 9 and to fixit to the ventilation wall 10. Moreover, as described above, theprotective shells 16 comprise tabs 61 for retaining the interconnectionplate 9 and thus also participate in optimally retaining theinterconnection plate 9.

In FIG. 5, the interconnection plate 9 is provided with a protectivecover 34 covering virtually the whole of its surface area to physicallyprotect it and electrically isolate it. The protective cover 34 is,furthermore, itself provided with ventilation through-orifices 35arranged opposite the ventilation orifices 29 of the interconnectionplate 9.

FIG. 6 is a schematic view in cross section showing the arrangementrelating to this first embodiment. In this FIG. 6, a module 6, shown insection, is mounted on a retaining seat. The casing delimited by theshelf 4 comprises an inlet duct 36 and an outlet duct 37 which areseparated by the flow separation wall 11.

In the present example, the support platform 5 is made up of twohorizontal flanges of the lateral profiles 32 forming two parallelplanar crossmembers on which the retaining seats bear. The upper part ofthe inlet duct 36 is closed by the retaining seats and the calibrationof the passage cross section for the cooling air distributed to themodule 6 is realized by the diameter and the number of the ventilationorifices 17 of the retaining seats.

As stated above in relation to FIG. 1, the inlet duct 36 distributesfresh air to the module 6 via the ventilation orifices 17 of theretaining seat, and the outlet duct 37 makes it possible to draw in thehot air which has passed through the module 6 which is situated on thebottom shelf (not shown). According to this first embodiment, this hotair is drawn into the outlet duct 37 successively through theventilation orifices 35 of the protective cover 34, then the ventilationorifices 29 of the interconnection plate 9, then ventilationthrough-orifices 38 of the ventilation wall 10, these orificespreferably being opposite one another as shown in FIG. 6.

In a variant of FIG. 6, the ventilation orifices 29 of theinterconnection plate 9 are smaller than the ventilation orifices 35, 38of the protective cover 34 and of the ventilation wall 10. Theventilation orifices 35, 38 of the protective cover 34 and of theventilation wall 10 are therefore oversized, whereas the ventilationorifices 29 of the interconnection plate 9 ensure the calibration of theair permeability of the inlet of the outlet duct 37. The calibration ofthis air permeability is an important element of the cooling systemwhich is determined during the design of the avionics bay, according tothe arrangement of the various elements allowing the generation and thechanneling of the cooling air. Since the calibration of thispermeability is realized by the interconnection plate, the shelves (andin particular the ventilation walls) and the protective covers 34 can bestandardized.

The interconnection plate 9 is directly fixed to the shelf 4 (or even tothe ventilation wall 10), with or without a tightness seal 53 or spacermaintaining a spacing between this wall 10 and the interconnection plate9. In the present example, the fixing of the interconnection plate 9 isensured by the reference potential setting fasteners 30.

FIGS. 7 to 9 illustrate one of the reference potential setting fasteners30 which make it possible to connect the interconnection plate 9 to thereference electrical potential and which allows the mechanical retentionof this interconnection plate 9.

The fastener 30 is a flexible fastener made up of a clamp formed by twojaws 39, 40 clamping the interconnection plate 9 between them. At leastone of the two faces of the interconnection plate 9 which is in contactwith the fastener 30 comprises a conductive ground pad 41. Theconductive tracks of the interconnection plate 9 which have to beconnected to the reference electrical potential of the avionics bayshould be electrically connected to this conductive pad 41.

The fastener 30 is made of an electrically conductive material suchthat, when the fastener 30 is clamped on the interconnection plate 9,electrical continuity is established between the conductive pad 41 and aheel 42 which is secured to one of the two jaws 39, 40. The heel 42comprises in its center an orifice allowing the passage of a fixingscrew 43.

Optionally, for better durability and connection security, the fastener30 is clamped by means of rivets 44 to the interconnection plate 9, andthe two jaws 39, 40 are clamped against one another by rivets 45 oneither side of the potential setting heel 42

An O-ring seal 46 may, moreover, be arranged around the potentialsetting heel 42 in order to seal the potential setting.

FIG. 8 shows in perspective a portion of one of the lateral profiles 32of the shelf 4, this portion being intended to receive the fixing of thefastener 30. To this end, the lateral profile 32 comprises a tongue 47electrically and mechanically connected to the lateral profile 32 forexample by welding or, as illustrated in FIG. 8, by riveting. The tongue47 comprises a crimped nut 48 so that it can cooperate with the fixingscrew 43.

FIG. 9 shows in section, at the fastener 30, the assembly of aninterconnection plate 9 and of a shelf 4. The fixing screw 43 is screwedand clamped on the crimped nut 48 such that the O-ring seal 46 iscompressed and the potential setting heel 42 is pressed against thetongue 47.

The fastener 30 thus affords mechanical retention of the interconnectionplate 9 without blocking it in place by virtue of the flexibility of thefastener 30 and of the tongue 47. This makes it possible to avoidmechanical stresses within the printed circuit constituting theinterconnection plate 9, and to achieve this while firmly retaining thisinterconnection plate 9. The mounting of the interconnection plate 9 andits reference potential setting are achieved by the mere operation ofclamping the fixing screw 43. In order to promote the placement of thefastener 30 with respect to the tongue 47, the fastener 30 comprises aflange 49, and the tongue 47 comprises a flange 50, these two flanges49, 50 being in flat-on-flat contact when the fixing screw 43 isopposite the crimped nut 48.

FIGS. 10 and 11 illustrate a variant embodiment of the referencepotential setting fastener 30. In this variant, the ventilation wall 10comprises a perpendicular flange 51, and the mounting of theinterconnection plate 9 opposite the ventilation wall 10 is realized byfixing the fastener 30 to this flange 51. The two jaws 39, 40 of thefastener 30 are here made up of parts in the form of an angle bracketwhich are adapted to clamp the interconnection plate 9 and to retain itperpendicularly to the flange 51 while ensuring the reference potentialsetting thereof.

The fasteners 30 deal with the need to resort to grades, cables andground terminals generally used in addition to the conventional printedcircuit fixing means.

The mounting and the connection of such an interconnection assembly to ashelf 4 is achieved by a very restricted number of operations reduced tothe fixing of the fasteners 30, 33 to the shelf 4, the fixing of theconnection walls 21 to the retaining seats 12, and the mounting of theexternal connection interface 7. These mounting operations are verylimited in number compared with the multiple cabling operationsnecessary in the avionics bays of the prior art, and this being achievedwith much greater connection security while limiting the risks of error.

FIG. 12 illustrates a second embodiment of the assembly of theinterconnection plate 9 with the rest of the shelf 4. According to thissecond embodiment, the ventilation wall 10 does not comprise ventilationorifices but instead comprises a ventilation window 52 creating a wideopening in the outlet duct 37. The interconnection plate 9 is hereproduced by a rigid and optionally reinforced printed circuit which isdirectly fixed to the shelf 4 while compressing a tightness seal 53. Inthis second embodiment, the calibration of the permeability defined forthe inlet of the outlet duct 37 is then realized by the number and thedimension of the ventilation orifices 29 of the interconnection plate 9.

This second embodiment makes it possible to lighten the shelf 4 by doingaway with virtually all of one of its walls (the ventilation wall 10)and by transferring this permeability calibration function to theinterconnection plate 9.

In the first and second embodiment, the fitting of the interconnectionplate 9 to the shelf 4 with the aid of the seal 53 makes it possible tosimplify the manufacture of the shelf 4 while allowing less precisegeometric tolerances and surface states insofar as the calibration ofthe cooling air permeability is directly realized by the interconnectionplate 9. The tightness seal 53 allows a relative movement between theinterconnection plate 9 and the shelf 4, thus preserving the integrityof the electronic card constituting the interconnection plate 9 underthe deformations and movements of the shelf 4 associated, for example,with the vibrations and stresses of the avionics bay.

FIG. 13 illustrates a third embodiment of the assembly of theinterconnection plate 9 with the rest of the shelf 4.

In this third embodiment, the ventilation wall 10 and theinterconnection plate 9 form one and the same piece which is produced ofan electrically nonconducting material, such as a polymer or a compositematerial. The interconnection plate 9 is formed by a wall closing offthe lower part of the shelf 4, on which wall the conductive connectiontracks 28 are etched, deposited or adhesively bonded.

According to this third embodiment, the mass and the cost of a shelf 4are reduced further still.

In a variant, the conductive connection tracks 28 can be integrated intothe thickness of the interconnection plate 9 by methods of the“plastronic” type.

Variant embodiments of the avionics bay which has been described may beenvisioned without departing from the scope of the invention. Forexample, the choice of a rigid interconnection plate 9 can lead toundersizing the shelf 4. It is possible, for example, to reduce thethicknesses provided for the walls of the shelf 4, and in particular thethickness of the ventilation wall 10, by taking into account theadditional rigidity afforded by the fixing of the interconnection plate9 to the shelf 4.

Likewise, if it is chosen for an interconnection plate 9 to be in theform of a flexible printed circuit, it is possible to provide a flexibleor even deformable shelf 4, the flexibility of the interconnection plate9 accompanying this deformation without inducing any stress which canharm the conductive connection tracks 28.

The protective shells 16 of the rear printed circuits 15 and theprotective covers 34 of the interconnection plate may, furthermore,provide electromagnetic compatibility functions, for example byelectromagnetically insulating the content thereof.

The integration of components in the front face of the shelf 4 is madepossible by the interconnection system. FIG. 6 thus illustrates anexample of the integration of an equipment item 54 in the facade of ashelf 4. This equipment item may, for example, comprise displays, relaysand command buttons. This facade equipment item 54 does not require anyother particular cabling than the addition of an additional flexibleprinted circuit 55 connected, on the one hand, to this facade equipmentitem 54 and, on the other hand, to the interconnection plate 9.

Moreover, ribbon cables may replace the flexible printed circuits 18, 19connecting the rear printed circuits 15 and the external connectionprinted circuit 26 to the interconnection plate 9.

1. An aircraft avionics bay (1) comprising an arrangement of racksintended for the integration of electrical equipment items andconnections, the avionics bay being provided with at least one shelf (4)which comprises: a support platform (5); retaining seats (12) for arackable electrical module (6), the retaining seats (12) being mountedon the support platform (5), each retaining seat (12) comprising an endwall (22) perpendicular to the support platform (5), and a moduleconnector (14) mounted on the end wall (22); an external connectioninterface (7) intended to be connected to the electrical circuit of theaircraft and mounted on the support platform (5) and connected to themodule connectors (14); wherein t said shelf (4) comprises: aninterconnection plate (9) extending substantially parallel to thesupport platform (5), on the side opposite to the retaining seats (12),the interconnection plate (9) bearing conductive connection tracks (28);a plurality of rear printed circuits (15), each rear printed circuit(15) extending opposite a module connector (14); the conductorconnection tracks (28) of the interconnection plate (9) extending intoeach rear printed circuit (15) and into the external connectioninterface (7) via flexible conductors (18, 19).
 2. The avionics bay asclaimed in claim 1, wherein each rear printed circuit (15) is fixed tothe module connector (14) opposite which it extends.
 3. The avionics bayas claimed in claim 2, wherein each rear printed circuit (15) and itscorresponding module connector (14) are fixed on either side of a spacer(23) and comprising a flange wall extending perpendicularly to the rearprinted circuit (15) and arranged on the periphery of the rear printedcircuit (15)
 4. (canceled)
 5. The avionics bay as claimed in claim 2,wherein each module connector (14) comprises pins (60) connected byrigid conductive rods (56) to the rear printed circuit (15) to which itis fixed.
 6. (canceled)
 7. (canceled)
 8. The avionics bay as claimed inclaim 5, wherein each retaining seat (12) comprises a connection window(20) made in the end wall (22), each module connector (14) comprising aconnection wall (21) which is fixed to the end wall (22) of thecorresponding retaining seat (12) by fixings screwed into the spacer(23), with the result that the module connector (14) projects from theconnection window (20).
 9. The avionics bay as claimed in claim 1,wherein each rear printed circuit (15) is connected to the conductiveconnection tracks (28) of the interconnection plate (9) by a flexibleprinted circuit (18).
 10. The avionics bay as claimed in claim 9,wherein the external connection interface (7) comprises an externalconnection printed circuit (26) to which interface connectors (8) areconnected, the external connection printed circuit (26) being connectedto the conductive connection tracks (28) of the interconnection plate(9) by a flexible printed circuit (19).
 11. The avionics bay as claimedin claim 10, wherein the external connection interface (7) comprises anexternal connection wall (25) fixed perpendicularly to the supportplatform (5), the interface connectors (8) and also the externalconnection printed circuit (26) being fixed to the connection wall (21).12. The avionics bay as claimed in either of claim 10, wherein eachinterface connector (8) comprises pins connected by rigid conductiverods to the external connection printed circuit (26).
 13. (canceled) 14.(canceled)
 15. The avionics bay as claimed in claim 9, wherein theflexible printed circuits (18) connected to the rear print circuits (15)are connected to the conductive connection tracks (26) of theinterconnection plate (9) via a detachable connector.
 16. The avionicsbay as claimed in claim 10, wherein the flexible printed circuit (19)connected to the external connection printed circuit (26) is connectedto the conductive connection tracks (28) of the interconnection plate(9) via a detachable connector.
 17. The avionics bay as claimed in claim10, wherein the interconnection plate (9), the rear printed circuits(15), the external connection printed circuit (26), and the flexibleprinted circuits (18,19) are formed by a single printed circuitcomprising rigid portions and flexible portions.
 18. The avionics bay asclaimed in claim 1, wherein the support platform (5) is made up of twoparallel planar crossmembers formed by two lateral profiles (32) of theshelf (4).
 19. The avionics bay as claimed in claim 1, wherein theinterconnection plate (9) is fixed to the shelf (4) by a flexiblereference potential setting fastener (30).
 20. (canceled)
 21. Theavionics bay as claimed in claim 1, wherein the interconnection plate(9) is made up of a rigid printed circuit in which the conductiveconnection tracks (28) are etched.
 22. The avionics bay as claimed inclaim 1, further comprising a device for cooling by circulation of a gaspassing through the rackable electrical modules (6), and in that saidshelf (4) comprises a ventilation wall (10) which extends parallel tothe support platform (5), the shelf (4) forming a ventilation casing ofthe cooling device, between the support platform (5) and the ventilationwall (10), the interconnection plate (9) being arranged opposite theventilation wall (10).
 23. The avionics bay as claimed in claim 22,wherein the ventilation wall (10) and the interconnection plate (9) eachcomprise ventilation through-orifices (38, 29).
 24. The avionics bay asclaimed in claim 23, wherein the interconnection plate (9) comprises asmany ventilation orifices (29) as the ventilation wall (10), eachventilation orifice (29) of the interconnection plates (9) beingopposite a ventilation orifice (38) of the ventilation wall (10). 25.(canceled)
 26. The avionics bay as claimed in claim 22, wherein theventilation wall (10) comprises a ventilation window (52), theinterconnection plate (9) closing off the ventilation window (52) andcomprising ventilation through-orifices (29).
 27. The avionics bay asclaimed in claim 26, wherein a tightness seal (53) is clamped betweenthe interconnection plate (9) and the ventilation wall (10), on theperiphery of the ventilation window (52).
 28. The avionics bay asclaimed in claim 26, wherein the interconnection plate (9) comprises aprotective cover (34) fixed to the shelf (4) and extending substantiallyover the whole surface of the interconnection plate (9), the protectivecover (34) comprising ventilation through-orifices (35).
 29. Theavionics bay as claimed in claim 28, wherein the protective cover (34)comprises as many ventilation orifices (35) as the interconnection plate(9), each ventilation orifice (35) of the protective cover (34) beingarranged opposite a ventilation orifice (29) of the interconnectionplate (9).
 30. (canceled)
 31. (canceled)
 32. (canceled)
 33. The avionicsbay as claimed in claim 1, further comprising a protective shell (16)for each rear printed circuit, the protective shell (16) comprising tabs(61) for retaining the interconnection plate (9).
 34. The avionics bayas claimed in claim 1, further comprising an equipment device (54) inthe facade of a shelf (4), the equipment device (54) being connected byan additional flexible printed circuit (55) to the interconnection plate(9).
 35. The avionics bay as claimed claim 1, further including a devicefor cooling by circulation of a gas passing through the rackableelectrical modules (6), and the shelf (4) forms a ventilation casing ofthe cooling device, the casing being delimited by the interconnectionplate (9) and the support platform (5), the interconnection plate (9)comprising ventilation through-orifices (29).